diff --git a/toardb/stationmeta/schemas.py b/toardb/stationmeta/schemas.py
index c34dfdfc0bc8c0506b562ccac459d33a41a0cd03..a18b5318e03d9e6c73a80150be522282594bcbb9 100644
--- a/toardb/stationmeta/schemas.py
+++ b/toardb/stationmeta/schemas.py
@@ -429,7 +429,7 @@ class StationmetaGlobalServiceBase(BaseModel):
     result_type: int = Field(..., description="Result type")
     result_nvalues: int = Field(..., description="Expected number of return values (1-16)")
     service_valid_year: int = Field(..., description="Year for which metadata are returned from this service URL or null if undefined")
-    service_url: str = Field(..., description="Service URL with %LAT% and %LON% placeholders to enter station or point location in floating point degrees")
+    service_url: str = Field(..., description="Service URL with %%LAT%% and %%LON%% placeholders to enter station or point location in floating point degrees")
 
 
 class StationmetaGlobalServiceCreate(StationmetaGlobalServiceBase):